Back spacing mechanism for typewriting machines



y 18, 1933- F. H. TREGO 1,918,304

BACK SPACING- MECHANISM FOR TYPEWRITING MACHINES Filed May 51; 1950 sSheets-Sheet 1 INVENTOR Fran/rd 771940.

A TTORNEY July 18, 1933. F. H. TREGO BACK SPACING MECHANISM FORTYPEWRITING MACHINES Filed May 31, 1930 3 Sheets-Sheet 2 INVENTOR far/7%Vega. BY a., ATTORNEY July 18, 1933. TREGO 1,918,304

BACK SPACING MECHANISM FOR TYPEWRITING MACHINES Filed May 31, 1930 3Sheets-Sheet 3 IN VE N TOR Fran/m! Treqo.

BY ATTORNEY Patented July 18, 1933 UNITED STATES PATENT OFFICE v FRANKE. TREGO, OF NEW YORK, N. Y., ASSIGNOR, BY HESNE ASSIGNMENTS, TO RALPHO. COXHEAD CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWAREBACK sracmo uacmrsm roa 'ryrnwm'rnra macnnms Application flled Iay 81,1980. Serial No. 457,676.

This invention relates to typewriting machines and more particularly toback-spacing mechanism therefor.

A feature of the invention relates to means including a ratchetassociated with a pinion element shiftable relatively to a feed rack forvariable spacing of the carriage, and a back spacer pawl to engage theratchet in any one of its shifted positions.

Other features and advantages will hereinafter appear.

In the drawings,

Fig. 1 is a sectional side view of the machine, some of the irrelativeparts thereof being omitted;

Fig. 2 is a sectional rear View of the machine, taken on the line 2-2 ofFig. 1;

Fig. 3 is a view similar to Fig. 2 but showing the back spacingmechanism operated sufliciently to swing the pawl into engagement withthe ratchet wheel;

Fig. 4 is also similar to Fig. 2 but showing the back spacing mechanismfully operated; and

Fig. 5 is a top plan view of Fig. 1, some of the parts being omitted.

Similar reference characters represent similar parts throughout theseveral views.

The invention is herein illustrated as ap plied to a typewriting machineknown as the Varityper, which includes a main-frame having a rail 11upon which is supported a carriage 12 thro h the medium of anti-frictionrollers or ba s 13.

A spring drum 14 is connected to said carriage by a strap 15 and urgesthe carriage in a letter-space direction (rightwardly in Fig.

2). A rack 16 on the carriage meshes with a pinion 17 secured to asleeve 18 provided with an internal ratchet 19 co-operating with aspring-pressed pawl 20 in a shaft 21 rotatively supported on the machineframe. An escapement wheel 22 is secured to the shaft 21 and forms partof the usual escapement mechanism 23 which is operated by the key-levers(not shown) to effect the letterspacing of the carriage.

To back-space the carriage 12 there is provided at the front of themachine and near the side thereof, a back-space key 24 which,

when depressed, swings a lever 25 about a gages a roller 28 on an arm 28secured to a rock-shaft 29, supported in lugs 30 on the main frame 10;said rock-shaft being operated, upon the depression of said key, in acounter clockwise direction (Fig. 2) to swing upwardly the free end ofan arm 31 on the rear end of said rock-shaft; the arm 31 being providedwith a roller 32 engaging a cam 33 at the end of a lever 34 to swing thelatter upwardly about a fixed pivot 35 against the action of a returnspring 36. It will be understood that by means of the cam 33 the lever34 is actuated through a greater extent, at its engaged efid, than themovement of the actuator or arm 31 at its engaging end.

A pawl 37 is pivotally supported b a stud 38 upon the lever 34 and isnorma ly held out of engagement with a ratchet wheel 39 by a stop 40; aspring 41 being effective to hold the pawl against said stop. During theinitial part of the actuation of the lever 34 the pawl 37 is carriedupwardly and the spring 41 swings the pawl about its pivot intoengagement with the ratchet 39 as indicated in Fig. 3.

Upon a further depression of the backspacer key 24 the pawl 37 rotatesthe ratchet 39 in a counter-clockwise direction, to the position in Fig.4, to thus back-space the carriage a single letter space; the pawl 20yielding during the back spacing operation to permit one of the teeth ofthe internal ratchet 19 to snap past said pawl. To the limit theactuation of the pawl 37 to its effective position there is provided anadjustable stop 44, for the key-lever 25, suitably secured to themachine frame 10.

When the back-spacing movement of the carriage has been completed andthe finger subsequently removed from the key 24, the spring 36, actingon the lever 34, becomes effective to restore the mechanism to normal.As soon as the pawl 37 engages the stop 40 it begins to swing out ofengagement with ratchet wheel 39 against the action of the spring 41.The key-lever 25 is guided in a comb plate 45a and is arrested in 1tsnormal position by a bar 45 secured to the top of said comb plate.

The pawl 37 is sufiiciently wide to prevent disengagement of the ratchet39 on the sleeve 18 which is shiftable lengthwise of the shaft 21, in amanner disclosed in my application ,No. 361,899, filed May 10, 1929, toshift any one of the pinions 17, 47 and 48 into engagement with the rack16 for variable letter spacing. It will be understood that by providingthe ratchet 39 on the sleeve the pinions 17, 47 and 48 may be actuatedby the back spacing mechanism so that the extent of back spacing of thecarriage always corresponds with the letter pacing efi'ected by theactive pinion.

Thus it will be understood that the backspacing mechanism comprises thekey-lever 25 which is a lever of the second order, the pawl carryinglever 37 which is also a lever of the second order and a lever of thefirst order formed by the rock-shaft 29 and its two arms 28 and 31; saidshaft extending fore-and-aft of the machine and the arms 28 and 31 beingdisposed at opposite ends thereof and extending in opposite directions,one into'engagement with the lever 34, the other extending to thekey-lever 25.

Having thus described the invention it will be understood thatalterations and changes may be made without departing from the spirit ofthe invention defined in the appended claims.

I claim 1. In a typewriting machine, the combination of a carriage,escapement mechanism including a ratchet, pinions connected to theratchet, a rack to engage anyone of said pinions, means to shift thepinions with the ratchet to carry the desired pinion into engagementwith said rack, and a back spacer pawl to engage said ratchet, said pawlbeing of sufiicient width to always engage the ratchet.

2. In a t ypewriting machine, the combination of a carriage, escapementmechanisms for said carriage, said escapement mechanism including asleeve including a plurality of pinions thereon, a ratchet wheel on saidsleeve, back spacing mechanism to engage said ratchet wheel, saidratchet wheel having a groove in its periphery, and means including anactuator to engage in said groove and shift said sleeve to connect thepinions differently with the carriage according to the desired letterspacing.

3. In a typewriting machine, the combination of a carriage, escapementmechanism for said carriage, said esca ement mechanism including asleeve inclu ing a plurality of pinions thereon, a ratchet wheel on saidsleeve, back spacing mechanism to engage said ratchet wheel, saidratchet wheel having a groove in its periphery, means including anactuator to engage in said groove and shift said sleeve to connect thepinions differently with the carriage according to the desired letterspacing, an internal ratchet on said ratchet an escapement shaft, and apawl on said shaft to engage said internal ratchet.

4. In a typewriting machine, the combination of a carriage, escapementmechanism for said carriage including a shaft, a sleeve on said shaft, aplurality of pinions secured to said sleeve, a rack on said carriage toengage any one of said pinions, means to shift the sleeve axially ofsaid shaft to carry any one of the pinions int'o cooperative relationwith said rack, and two cooperative elements to back space the carriage,namely a ratchet secured to said sleeve, and a pawl to enga e theratchet, one of said elements being su ciently wide to engage the otherin any position of the sleeve.

' FRANK H. TREGO.

